Promising pesticides get a taste of real life

Promising pesticides get a taste of real life


By Lila Guterman DRUGS companies have led the way in fast, high-volume testing of experimental compounds. Now a pesticides manufacturer is making the process even faster. Zeneca Agrochemicals in Bracknell has developed what it calls “high throughput” screening methods that test compounds on entire organisms. Since the early 1990s, the pharmaceuticals industry has pioneered the use of “combinatorial chemistry” for making and screening huge numbers of compounds. Companies regularly produce many slightly varying compounds then screen them, 96 at a time, to see which ones bind to an enzyme important in disease. The ones that pass this preliminary test go on to be tested in cells, tissues and, ultimately, in whole organisms. Now the pesticide industry is developing preliminary tests for herbicides, fungicides and insecticides that bypass all these stages, and use entire organisms at the first go. If the technique suits the tiny insects, plants and fungi, which can fit in the centimetre-sized wells, they only require testing with small amounts of chemicals to show which are effective. John Ormrod, the biologist leading the project at Zeneca, says that testing on whole organisms mimics real-life use of the compounds much more closely and makes it more accurate. Cutting out the enzyme screening also saves time: a compound that affects an enzyme may fail in the organism, where it may be broken down. Ormrod says high throughput screening could be used for the other tests that pesticides must go through before they are marketed. Apart from killing the pest, a desirable pesticide should not be toxic to other organisms and should not linger in the soil. “In all these areas of testing, we will inevitably get into miniaturisation. It’s an ambition for the future,
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